Process for the conversion of hydrocarbon oils



Aug. 27, 1946. H, z, MARTIN PROCESS FOR THE CONVERSION OF HYDROCARBONOILS 2 sheets-snee; 1

Filed Sep'l..A l5, 1941 Patented Aug. 27, 1946 UNITED STATES PATENTOFFICE PROCESS FOR THE CONVERSION 'OF HYDROCARBQN lOILS Homer Z. Martin,Elizabeth, N. J., assignor to Standard Oil Development Company, acorporation of Delaware Application September 13, 1941, Serial No.410,657

residualoils, into motor fuel constituents. 5 quent intervals. In othercases, when operating It has been heretofore proposed 'to crack oils to.form a coke residue it has been the practice in the presence of avcracking catalyst to form 'to collect .the coke formed in .separatecoking gasoline of relatively .high octane rat-ing. vessels from Whichthe coke may be, .removed According to one general mode of operation,the by mechanical means. A oil in vapor formis passed through a crackingl0 In all of the above cases, the treatment of zone containing -a xedmass of catalyst7 preferthis residual ,fraction for production ofadditional 'ably in the 'form of pellets or molded units, loquantitiesoffgasoline has required a considerable cated Wit-hin the .reactor andsupported on a investment in additional equipment. perforated tray or aplurality of trays. During One of the primary objects of thevpresentinthe cracking process the activity of the catalyst '11:5 vention yis toprovide .a process .for catalytically rapidly depreciates due to theformation oicart bonaceous deposits. In View of this, .it is necessaryin xsuch operations to interrupt the crack# ing process frequently .andregenerate the :catalyst mass by burning the carbonaceous deposits.

therefrom. In order to avoid the forma-tion of excessive -coke deposits,which in turn reduces the productive capacity of the cracking chamber,it has been the practice to first vdistill and fracit has also beensuggested to lcarry out the coking treatment in the presence .of arelatively inert solid material which forms a carrier for the coke andfrom which the coke maybe -bu-rnedat .fre-

craeking crude oils to the desired vconversion in a single stage without.the necessity .of first separating a .heavy residual fractiontherefrom.

A further important object .of the invention vis to provide .an.improved process for cracking crude yoils or residual .oils which Willrequire .less etpiipinent .for .a .cracking plant :of .given capacityand for va given quantity of .motor fuel produced.

A fur-ther secondary object of the invention tionate 'the crude Ioil andto pass only the cleanl -25 is to provide an improved process andapparatus vapors in contact with the catalyst and to reject for crackingresidual oils which will .take .better a heavy residual fraction whichtends to form advantage; Yof the heat liberated during .the reexcessiveamounts of coke during the cracking generation'of the catalyst .forcarrying out the process. This method Vof operating-not only recrackingprocess.. Y 1 f quires the provision of diS'tilli-ng equipment for '30Other more .specific objects oi' the .invention preparing a clean feedstock .for the cracking Will be apparent from the more .detaileddescrip- 'process but also requires the `rejection of a subtionthereinafter. f v v stantial amount of the original feed .in the form Inaccordance with the broader phases of the of a residue which is notnormally suitable for present invention, ac-ruderesi-dual fraction, suchcracking treatment for the production of Ihigh 35 as a topped -orreduced crude, or, in certain cases, octane `gasoline Without additionalprocessing. the `entire crude, is contacted with ahotadsorp- Thisrejected fraction may amount to from 5% -tive catalyst in subdividedstate at a materially to 40% of the original crude, depending upon thehigher temperature level than the oil, the amount nature of the `crudeoil. This residual product of catalyst being ycontrolled with respect tothe 'in many cases is consequently marketed as fa, 40 temperaturethereof so that the oil upon contact heavy fuel oil. with the catalystis promptly converted into va- However, this residual fraction containsa subp'ors, except for some residual oil which is `cornstantial portion.of oil 'which can be :converted pletely adsorbed by the `catalystwithoutcausing into high-grade Ygasoline with additional processthelatter to become tacky .or sticky. V- The -reing. For example, it hasbeen the practice ,in 45 `sult-ing mixture, therefore, consists ofrelatively some cases to sub-ject this heavy residual rrac- `dry oil'vapors 4and discrete particles of catalyst tion to a yseparate yand:independent (cracking 'or containing the heavy constituents adsorbedviscosity breaking treatment to convert the same therein. y into themaximum of overhead vapors suitable The resulting ydispersion Iof.catalyst powder for .further cracking under con'ditions controlled 50containing the residual constituents adsorbed for .the product-ion ofimproved octane gasoline. In other leases; it has been the practice toconvert all of this residual fraction into overhead vapors suitable vfor,further cracking with the exception of the Ycoke residue. In the lattercase,

therein and the oil vapors .is then passed through va cracking .chamberin which the desired .con- Version is accomplished.

As distinguished from viscosity breaking oper atiQns of the typehereinbefore described, the

ating zone.

iparatus suitable for carrying the invention eii'ect, and

present invention contemplates the conversion of Va substantial'portionamounting to at least 30% oil vapors are retained within the crackingzone.

This makes possible a greater utilization of the i catalvst between-regenerations and permitsV retaining the catalyst within the crackingzone until its activity has dropped to a point Vwhere regeneration ofthe catalyst is desired.

` This retention of the catalyst within the cracking zone for a periodsubstantially longer than l designates a charge line through which theoil to be processed is introduced into the equipment. This oil may be,as previously described, a residual oil, such as a crude petroleum, `or

products from the process.

so introduced may be forced by feed pump Il through line I2 toa trimmingcoil I3 located in the top of product fractionator I4 in which the thetime of residence of the oil vapors therein Y Following the crackingprocess. the catalyst is` separated from the cracked products eitherwithin or without the cracking zone and the cracked productsvfractionated in a conventional manner to segregate the desiredproducts.

The catalyst so separated is then regeneratedV to remove thecarbonaceous deposits formed durling the cracking treatment. Theregeneration lof the catalyst is preferably carried out at the `maximumpremissible temperature which will `avoid permanently impairing theactivity of the catalyst so as to make available for the crackingvoperation the maximum amount of heat liberated Iduring the regenerativetreatment and the catalyst so regenerated is immediately contacted `withthe oil while at substantially its maximum regenerating temperature. Inorder to operate the regenerating chamber at the maximum temperaturelevel. it is important vto avoid localized overheating of the catalystwithin the regener- This is accomplished, `according to one of` thespecific phases of the invention. by

constantly agitating or churning the catalyst within the regeneratingzone, and. according to one of -the additional'phases of the invention,

this agitation or churning is accomplished by the flow of theregenerating gas through the re- Having set forth the general nature.objects ,and advantages, the invention will be described' in more detailin which reference will be made to the accompanying drawings wherein-Fig. I is a diagrammatic illustration of an apinto Fig. II is a similarView of a simplified apparatus wherein the total heat requirements forlcarrying out the process are obtained by direct contact with hotcatalyst.

Referring toiFig. I, the reference character I0 cracked products arefractionated. The oil after passing through the coil I3 may be passedthrough line I5 to a second heat exchange coil IB located in the bottomportion of the fractionating ytower I4 or in a heat exchanger associatedwith the bottom portion of the fractionating tower. -The oil afterVpassing through the second preheating coil I6 may then be passedthrough line I1 to a heat exchanger I8 wherein it passes in heatAexchange relation with spent regenerating gases removed from theregenerating zone, as hereinafter described. The oil after passingthrough the heat exchanger I8 is passed through line` I9 to a heatexchanger 20 where it passes in indirect heat exchange relation with''hot catalyst undergoing regeneration. l

The oil after passing through heat exchanger 20 is transferred throughline 2l to a second heat exchanger 22 wherein it picks up additionalheat from hot catalyst undergoing regeneration as later described. y -YWhen operating on total crudes containing substantial amounts ofgasoline, it may. be desirable in some cases to rst distillthestraightrun gasoline. For example, in lieu of passing the crude loilin heat exchangewith cracked products in the product fractionator I3,crude oil introduced through line I0 maypass through line 23 to a crudestillZlI wherein the oil'is heated to a temperature of from 400 F. to600 F., sufrating chamber 25 wherein the vapors formed separate from theremaining liquid. The vapors in separator 25 pass overhead to acondenser 26 wherein the straight-run` gasoline vapors or other lowboiling vapors are liqueed. Products from condenser then pass to adistillate receiver 21. Liquid is Withdrawn from yseparator .25 throughline 28 which merges with feed line I'I.

The oil duringV its passage through the heat exchangers and crude stillhereinbefore described.

` or any combination thereof, is preferably preheated to a temperatureof from 400 F. to an incipient cracking temperature, such as, forexample, to a temperature of from 700 F. to 800 F. The oil after beingpreheated to a temperature of from 400 F. to 800 F. by passing throughone or more of the .various heat exchangers is passed f located at Vapoint preceding the catalyst dis'- charge line 30. For example, thepressure on the oil passing through the preheating equipment may rangebetween 50 and 500 pounds per square For example, the oil lamme-e should:not be iin fexcess '.of that lwhichiican be Acompletely adsorbed by thecatalyst particles `without causing the catalyst .particles to become.adhesive :and 4iorm :a 44Vtacky, .sticky mass. :The .amount .of suchIcatalyst introduced into the foil :vapors 4will Idepend 'upon :thetemperature iof :the :catalyst and lthe :temperature of the .foil at theyplacedzhecatalystisrnixedwithithezoii. l EIllre famount 'of .catalystintroduced "into the-oil stream may .range :between .1 .and =45 4parts-zof catalyst per part fof'oilbyrveightpdepending upon ".the fnatureiof'ftlreoil,y temperature :of fthe catalyst, theldegree'o'f:pretreatment andsother factors. In most 1cases the 'zratio will .':belbetween 5 `andt20.

uThis VYcatalyst may comprise any vradsorptive :material capable yof:catalytically effecting the y.cra-'cking operation. vSuch material maycomprise, for-.example Anatural clays for 'clays which `have fb'een.activated Eby suitable 4Itreatm'ent, Lsuch as with fa'cid, fto remove:impurities which may affect vthe fcracking or regenerative 'propertiesof 'fthe catalyst. .Inlieu ofthematural materialsuc'h Yas clays, 'thecatalyst may :consist `of synthetic adsorbent materials, such Jas, forexam-ple, I synthetic .gels of silica fand-alumina or silica andmagnesia, alumina, lboric :oxide fand others.

YThe .cata1yst introduced "into the 'oil stream rshould be in subdividedestate, the size of the particles ranging :from a nne powder, such fas'400 zmesh or finer, up to relatively .coarse lgranules, such as from 5to 10.mes`h.

"The resulting -dispersion "consisting vessentially of oil vapors whichhave been fvaporized by contacting with the Iho't "catalyst land byreduction fin pressure througlhftlre lreducir-1g valve i3! and 'thecatalyst containing the 'unyaporiza'ble constitu- 'ents of .the .oil'adsorbed 'therein "is ipassedithrough erably in the :form .of =avertical tower through which the dispersion isftorced to pass in 'aniupward Ydirection against the tforce iof gravity. 'The lower 4portionofthe cracking :chamber T33 may fbe provided 'with va .perforated plateF34 below which is ,a portion of reduced diameter.. ".Ihe yelo'city .oflfthe oil'stream Lpassing upwardly through the cracking chamber .'33 ilspreferably 4controlled so that .the catalyst .contained in the streamy-of 'o'il vap ors iten'ds to Ysettle 'from :the ga's stream. As vra"result, the idensity I*ofi-the #catalyst fwithinthe re- "actor-fis'm-aterially greater thanv 4is the density lin thefstreamof'oil in*the lfeed line 32"1e'adirig thereto; The ydensity :in 'the reactor,rorexamplefmay rrange from 5to 20 pounds per vcubic-'foot "in cases .fofactivated clays, Whereas the V.density of the nfgiven .regenerationtemperature to -slmplyithe .heat- 1 f i 1 fatter l.passing through #thecrack-ing chamber Agasp'line .constituents are liqueed '.T-hefstream :offcracked products :and mil iis .passed through "Iin'e :3.5k :to Avaprimary separator 136 :for the separation :of 'the catalystk from ithe.cracked vapcrproducts. This:separatormayhe lof a'ny conventional type:suitable .'for .segregation :of solidsaffrom vgai'ses .fand .ih-as.been illustrated .The #catalyst *the formcf a cyclone separator.

removed from the cracked products during pas- 'sage 'through the primaryseparator `3B discharges -in-to fa vertical ftube T31 :from `whence .itis passed Y :to :a regenerating chamber, 'as flater described.

.'Illre `cracked Wapors after having the .bulk `rif the catalyst'removedtherefrom in :the :primary :separator v:maybe passedzthrough line 38tera secondary separator :39 '.f'or urther removal iof the catalystmaterial. l,'Ihe 'fcatalystfseparated in 'the :secondary separaltor 39'discharges Athrough .line 40 :finto the bottom section fof the :primary:separator '.36 where it imixes'with catalyst sepa- .irated in the'primary cyclone :36. The .bottom portion fof .the :primary .separator13.6 may "be provided -with suiiicient volume ito form va :storage.hopper capable of maintaining v'a reserve `supply iof catalystfor 'theprocess. .Steam for Iother stripping :gas may vbe'iritroduced into thebottom 'of :the separator -36 through line "4| to 'strip 'volatilevcracked 'products ifr'om 'the 'catalyst beforepassin'g the same to :theregenerating zone.

z'Ilhe :cracked 'vapors fatter passing throug'hithe 'secondary separatorl39 ma'y be passed vfto iad'die `tional cyclones,electricalprecipitatorsibag'lters, or l.other separators (not shown)Afor'furtlrier fpurification. The cracked products fatter separationfrom :the -natalyst are 'passed ".:fthrough llinel' to :the Aproduct'tractiona'tor il!!! wherein `vthe cracked 'products :areafractionallyicond'ensed to segregate.

the :insufliciently .criacked' 'constituents as conydensate. The shear/ycondensatefformed in fthe .bottom section fof fthe ijfra'cti'onating4'tower' fil-fis Withdrawn ttherefromwthrough "line M 1and may rberemoved :from the system-or 'it may be lcoin- ?bined witntreshiiieedthrough dine M vand pump :d5 `for funthercraohing fitreatment. lmaterial may :contain "..traces .of the catalyst employed "in the-cracking'operation which are not completely removed in fthe separatingiequipment. By lrecycling this .fractionto .the cracking equipment, .thecatalyst contained therein may be 'returned ltoitheprorcess. @ne ormorecondensates formed .in thefractionating tower '14 may lbe ycolllectedin'trap-'out itra'ysfllf and '41V :and vremoved ffroni the systemthrough-lines I"48 :and 9, frespectively.` -For l .exampleaDieseLheating or fumac'eloi-l-may be collected in: the vtop 'trap-out Itrayv'M and a :gas -oilifractionimay be collected in the trap-'out trayd; if

` '.The'orackedyapors remaininguncondensed in v thezproduct-fractichater 1"4 and containing the- 4.bulk 'of l'the gasoline'constituents 4iorm'ed during the ioperation pass `overhead Tt'hrough.linegzol lto .-'a'product condenser ISZ 'inifwhicl the y 'Products:from the :ic 'ensei' i532 pass fto 1a receiver f53'in which ftle .fiquid forrned 'in the condenser 52 segregates ifi-om normallygaseousconstituents formed during the cracking mloeratiofi. The

liquid distillate separatedin 'i'fhefprcduct'receiver 513 `may bekW"tl-i'draxyn "therefrom ithrough fline 54 and the norm-allygaseous'constituents 'may jbe Withdrawn 'through .line 55 andfpassedto asuituableiabsorptionL-or :recorre-ry' .equipment -iorzfremoying`normally @liquid constituents'. :entifa'ined` A"therei'nc -V Returningtofnolumn' A3?! :receiying spent catalyst l v alyst forreturn to the'cracking Zone. 1 other inert strippinggas may be introducedinto` thebottom of the hopper 65 through line 65 to remove regenerating gas fromthe catalyst before f. returning the catalyst to the cracking processand -to maintain-the catalyst in a fluidized condition. The bottom ofthe center hopper or'compartment 1 65 isin open'communication withcatalyst tube 30 which-in turn-discharges into the The velocity, oftheoxidizing .gas -passing 'through the regenerating chamber: 58 ispreferably adjusted to permitthe Vcatalyst particles to ji'orm into arelatively densebed of kcatalyst .within i the. regenerating chamberthrough which the regeneratingA gas must pass.- By'regulating thevelocity of the regenerating gas passing through '"st'ream f of.;catalyst and regenerating. .1 gas.

distribution. i q f As previously vantage to transferheat from hotregenerated `'Ihe annular spacg below the perforated plate will then.form a. distributing zonefor the catalystfgas suspension passing ontothe main bodycf the -regenerating chamber; VItiis sometimes, desirableto introduce thefincoming stream ataplurality of points around theannular space to improve wset forth, it is sometimesof ad--cataly'st'tothe fresh oil feed in indirect heat exthe regeneratingchamber within certain limits,

the catalyst bed or mass within the regenerating l --chamber may be madetoassume the appearance vof a violently boiling liquid so that the`catalyst --particles are continuously and thoroughly mixed.

` -As la result, a `substantially uniform temperature may be maintainedthroughoutthe full depth of 3 the catalyst mass and localizedoverheating can be avoided. The velocity of the regenerating gas passingthrough the `regen-erator may beni thel -order of from 1/2 to 10 feetpersecond, depending upon the size cf the catalyst particles, densityand other factors. For example, when yemploying activated clays having aparticle size between- 200 and 400 standard mesh, the velocity of theregenerating gas passing through the regenerator 1 .should be between 1and 5 Vieet per second to .obtain the above-mentioned results.

j, I'he ,spent regenerating 1 gas after passing;` I :through theregenerator 58 isremoved overhead r--through line 59 andv is passed to'aseparator 6l] .in which catalyst powder `entrained inthe gas isseparated from the regenerating-gases. The catvalyst.powder-collectedinthe separator 60 is removed through line 6| and returned to the regen-.erator- 5B- The regenerating gas after 'passing Vthrough the separator60 passes through line'62 to thev heat exchanger. I8 through which itmay pass-inindirect lheat exchange relation-with thev `fresh feed, aspreviously described. The regen-` erating gasY isV removedfrom the heatexchanger I 8 through line 63 and may bepassed to additional separatingequipment, such agan electrical V,precipitator -(not shown) for removingfinali traces of catalyst powder.` ThisV regenerating gas may also lbepassedto a' waste heat boiler or other wheat, recovery `equipment "(notshown) 5 Referring again to the regenerator v58, the bot--tom-section'of the chamber is provided with aver-1. tical, circularpartition wall spacedtfrom' the outer wall ofthe chamber to form acentral comparta Steam orv oil feed line through a control valve61.

y The stream of regenerating-gasand spentcaty .l V.alyst from thecracking process passing'th'rough `line 51 is introduced into theregenerating cham` -ber-58 in the annular space between the circularportion Gland the outer wall of fthe regenerating chamber. An annularperforated plate'68-may be,;provided above-the.' inlet Lfor. the.incoming i changers and 22,7'althoughthis step .maybe omitted inmanycases, as laterdescribed. :To this end hot regenerated catalystvcollected inthe :central hopper 65 of regenerating chamber58 may beWithdrawn through tubes 69 and 16 and discharged into a stream ofregenerating' gas such -as air or inertgas-introduced through linesflland '12, respectively,'which--carries'the hot -acatalyst throughv lines13- and 14 into heat exchangers 2l) and -22 where it passes inindirectheat ex-V changev with fresh-.feed as previouslydescribed.

The l.suspension oihotL regenerating gasr after passing through heatexchangers 20 and 22is returned to the regenerating-@chamber throughlines 80 and '15.below'the'perforated .plate 68'.'

- The invention, as previously described, involves the stepof preheatingthe oil by indirect Contact Y with hot catalyst and then contacting withhot catalyst :to complete the heating. While 4this method of operatinghas denite advantages. in many cases, the invention also-contemplatesthe -omission of the preheating step 'by indirect heat .ingzone into theoil stream. Y Referring to Fig'. II, for-purposes of and brevity partscorresponding to those show-n exchange in catalystheat exchangers 20and22. When operating in'thismanner, heat;` exchangers 26 and22 may beomitted ora part or all of the feed oil after passing through heatAexchanger I8 may be by-passed around the heat exchangers 29 and 22through line 16. i* Fig. II illustrates afsimpliied Vform-of'I apparatuswherein the tota1 heat requirements 'for the cracking operationarevsupplied by direct injectionof hot catalyst removed'fromftheregeneratin Fig.V I have been identiiied by prime numbers.

NfIn Fig'. II,-the oilV to, be charged, which may be through line* Hl".

ya 'topped-crude 0r any type of -feed stock mentioned hereinbef'ore, isvintroduced intothe sys'-y tem at :substantially vatmosphericvtemperature Y The oil; with or without being first preheatedbypassing-:in heatl exchangeV with products undergoing fractionationYinl heat exchange coils v`|3- and-I6 isi transferred through vline ll'vvinto whichjthe-hotv solid material is' introducedthrough conduit 60.provided Vwithj-a l mentor hopper for collecting regenerated catfcontrol va-lve 51.. vThe"result'iirgf'mixture of .-oil

Y and solids-then passes through' conduit 32'to the reaction chamber33,' of-construction-similar to reaction chamber 33 shownin Fig.'r I."Theflovv of the mixture through the-reaction chamberand subsequentseparating and. fractionatinggequipment is the same asfthat illustratedin Fig i-I.

In this'case, the-amount of hot catalyst 'introduced into the relativelycool oil stream'passing :through transfer line'l'' is-sufcient to heatthe :,oil to thev desiredcracking temperature'an'dfto supply thenecessary heatfor'the cracking process. 'Expressed' in vanother/Way, theamount of solid' material sc introduced is controlled to' ob- ."tainthedesired heating.-V Theactu'alamount of :fsolid material may beof theorder of from y10 "partei-of. solid material per part"'ofoilvup'toi-l)or more parts of solidmaterial per part ofi-oil.

simplicity' 9.. For example, when cracking an East Texas re.- ducedcrude at4 a. temperature, ofr about. 9509 F. and regenerating the solidmaterial ata temperature between 1150 F. Yand 1200? E., the amount. ofsolid material introduced into the oil stream will beof` the order offrom 15 to20` parts @solid-per part of oil.. u A

. By comparing the amountof equipment shown.

in Fig. n with vthat iuustratedgin Fig. I.. it will catalyst mustbeadded. tothe oi-l than is the case when. ai part of the heat issuppliedby indirect heatexchange in heat exchangers 20.and 22. Expressed, inanother way,` when operating without the h'eat exchangers 20 and 2-2substantially all` of thev heat liberated during. regeneration, exceptthat. taken out byA regenerating` gas, mustobe absorbed by the catalystpassing tothe feed oil; Consequently, when operating in thismanner theamount ofA hot. catalyst added to the oil must bev such that the amount.of catalyst employed. in

proportion to the amount of coke formed` in the; cracking zoneissuicientto absorb substantially all the. heat liberated duringregeneration.y In.v some cases the amount. of. catalyst necessary to.supply the heat requirements for the cracking'` processl mayresult-inexcessive` catalyst lossegandcause. excessive cracking. resulting in theformation? of undesirable amounts. of lowgrade products,.lsuch as gasand. coke.. In.Y such cases a part of the catalyst may be` replaced byrelatively inert heat absorbent materials such as` pumice, fullers'earth, bauxite, diatomaceous. earth, and-sand whichl have little if anycatalytic inuence on the reaction. The amount of such inert solids mayrange from to 90% of the total solids circulated, depending upon anumber of factors, such as the nature of feed stock, amount of cokeformed, activity of the catalyst, temperature of cracking and ofregeneration, rate of ycirculation and other factors. For example, whencracking an East Texas reduced crude at a temperature of 980 F. withacid-treated clay wherein about 5.5% of the'oil is converted to carbonwhich is retained on the solids, approximately 45 parts of solids heatedto 1050 F. by regeneration will be required to preheat the oil from roomtemperature to final cracking temperature and for supplying thenecessary heat for cracking. In such a case it will be desirable toreplace a part of the catalyst with less expensive inert material. Itwill be understood, however, that by regenerating at a highertemperature or by employing feeds which produce less coke under a givenset of conditions the amount of solids necessary. to supply the heat canbe materially reduced. As a further example, when regenerating at 1150F. rather than 1050 F. the amount of solids to supply the required heatmay be reduced from 45 parts to about parts, other conditions being thesame.

In some cases, the amount of heat liberated during the regeneration maybe more than sufficient to carry out the cracking operation. In

1-0y such cases. a. portion of the.A oil4 afterl circulating. through.the heat,v exchangers 21). and. 22. may. be.- passed through line 'Illand. pump-1.8. te. an. addi. tional. heat.. exchanger 1.9,. which maybe inthe form of a waste heat boiler.

The. oil.4 after passing, through; thef heat. ex-

changer lY i'sr transferred; through line. 8 to.. line. l andr is4returned. to. the inlet side of.; heat.. ex-..

changers 2ll-andi2.2.. t y

The pressure. necessary. totransfer the catalyst from the regeneratingchamber to the oil stream. inline. 32. is. developed.. accordingE tothe/preferred. embodiment. ofi the invention., by.v con-.-

structing the. catalyst.conduitlllofvv such height.

that. the. combined height of the catalyst within the. regenerat'or.and. in: thev conduit. 30. sufli.-Y

cient to. build up. hydrostatic. pressure. somewhat in excess` of the.pressureon the oil; vapors atthe.-

point. of entry of I the-.'cata1yst. therein. Like-.

wise the pressure-necessary to. transfer the.- cat.-

alyst into.- ther regenerating gas.` stream in. line. 51. may.V be.developedv by constructing the. feed, conduit of aheightorelevationsufcient to. bui-1d,- up a hydrostatic pressure somewhat. invexcess: of. the. pressure. on` the` regenerating gasA4 atthe point. ofentry ofthe'spent catalyst.v therein... This-will.- insure proper ow of.regenerating gas, and-oil.- and prevent. by-.passing of. oilinto. theyregenerating` zone. and vice. versa. In. order. to. transmit thepressure` through the. standpipes or catalyst feed conduits, 30v andv3.1. the.` catalyst. should bef maintained inafreely ovving statetherein.l In some cases. anfluidizing, gasmay be introducedA at one ormore spaced. points. along the conduitsto maintain the catalysty in,fluidized condition. It-

may also be. desirable. to. introduce. aV fluidizing gas at. all.'points the system. where. the,4 catalyst. is. segregated fromthe. gas.stream.k

Tofavoid. reducing and building4 up pressures. 010.I the. C2L3J5`-SI2vpassing back andl forthffrom thev regenerating, chamber. to. the..cracking chamber, it iS of advantage. to. operate, bothithe. crackingandthe. regeneration processi at. substantially.' the. same pressurelevelexcept for the pressure drop, inherent inthe iiow,..'and.it.isfa1soof advantage. tomaintain the pressure drop through the system at aminimum so as to reduce the height of tubes 3i and 3i) employed fordeveloping the required'pressure. The passageof the cracked vapors andregenerating gas through the cracking and regenerating Zones at a lowVelocity as previously described, tends to reduce the pressure It willbe understood that the height of the :feed conduits S and 3l does notdepend on total pressure on the system but the pressure drop through thesystem and the pressure diierential between the cracking andregenerating zones so that any desired total pressure may be maintainedin the circuit.

In some cases the amount of coke formed during the cracking operationmay be insuiicient to generate the required heat during regeneration topreheat, vaporize and carry out the cracking process. In such cases,additional heat may be supplied to the regenerator either by externalheating or by adding a combustible yfuel into the stream of regeneratinggas. However, in most instances the amount of coke formed during thecracking treatment will be suiiicient for heating v the oil.

The present invention also contemplates `absorbing the excess heatformed during regeneration by admixing With the catalyst aV relatively,inert inaterial capable of absorbing' substantial quantities of heatliberated during the cracking' process; ""ThisY inert adsorbentAmateria1 can be utilized for carrying lheat from the regenerator 58 tothe cracking'equipment.' Y Having described the preferred embodiment ofthe'invention, it will be understood that "it embraces such othervariations'and modifications as come Within the spirit and scopethereof.l 'n

What is desired to be protected by Letters Patent" isz" ILInv a processof cat'alytically converting resid--A ual foils 1 containingconstituents unvaporizable Without substantial decomposition into motorfuel wherein the oil is'oracked 1in the presence of aV solid adsorbentcatalyst injsubdividedgform and the lcatalystfr egenerated Yat V atemperature higher than the cracking temperature; the method whichcomprises passing the residual oil to be cracked in'ii'direct heatexchange relation With'regenerated catalyst to thereby preheat said oiland cool saidrcataly'st, returning said cooled vregenerated `catalyst tothe regenerating zone, mixing' saidoill temperature, the amount andtemperature'v of the catalyst so introduced being Vsuiiifcient to heatsaid oil above VStill" F. and'completely absorb the uri.- vaporizableconstituents contained therein Vt0 thereby form a relativelydrysuspension Vof` il vapors and catalyst;niaintainingthe oil vapors nin contact with the catalyst 'within said cracking* zone for aperiodsuicienttocrack at-'least30%A thereof into motorfuel constituents,conti-nvufously'-A separating a stream of finely divided catalyst'con-`taining solid combustible deposits from theoilva-j'V pors, thereafterfractionating" the oil vapors to segregate a motor fuel fractiontherefromfen-L tinuously passing a stream of saidjcatalyst sep aratedfrom said oil'vapors -into a regeneratingzone, passinga stream ofoxidizing gasupwardly through 4said rzone at avelocity limited'toform adense, turbulent bed of catalytic material and:

oxidizing gas in the bottom'sectionoffsaid regenerating "zone,y burningcombustible deposits from the nely divided catalyst Withinsaidregeneratv Vingzone to thereby heatsaid catalyst to a temwithregenerated"cata1yst1vvhile saidcatalyst is at substantially theregenerating temperature,

adding sufiic'ientcatalyst to said oiltosupply al1 Y lof then/additional'heat necessary for crackingsaid Io'il and completely adsorb al1 oilconstituents re-j `maining unvaporized at the mixing temperature,passingithe resulting mixture through a crack' ling zone, maintainingsaid oil vapors Within said cracking zone to obtain the desired crackingthereof,VV separating the cracked products from the catalyst and-fractionating the cracked produots `toy segregate the desired fractiontherefrom. 2. 5A process for the catalytic cracking of heavyresidualoils containing ar substantial portion of constituentsunvaporizable Without decomposi- 1tion tofform lower boilinghydrocarbons inthe `motor-fuelV boiling range Whichcomprises passing astream of said residual oil through a cracking l zonel introducing astream of'hot regenerated cat- 1 alyst While said catalyst is atsubstantially regenerating temperature 'into said stream of oil while lsaid oil vis at a temperaturebelow active cracking perature "above thetemperature maintained in said cracking zone but below the deactivationtemperature of said catalyst, the density'and turbulence of thecatalyticA material Within said regenerating zone being sucient tomaintain a:

substantially iuniform temperature throughout'- they regenerating zone,continuously withdrawingA a stream of regenerated catalyst from theregenerating zone and continuously returning said catalyst to said oilstream while at substantially its catalyst therein and maintaining thecatalyst within said column in a free flowing i'luidized n state. '1

' l HOMER Z.

